Probiotic bacteria, mainly lactic acid bacteria (LAB) (e.g. lactobacilli, lactococci, enterococci, and bifidobacteria) have been considered safe for human consumption. However, recent reports of clinical infection, the spread of antibiotic resistance genes, and development of new and/or modified probiotic LAB strains, have caused concern of safety. This project aims to assess the biosafety of LAB. Isolates from healthy humans and immunocompromised patients, commercially available and new probiotic LAB will be studied. After polyphasic taxonomic identification, their biosafety will be assessed by several methods (see objectives). The project will result in recommendations for biosafe and biosafety testing of LAB.

Objectives

Overall objective: The safe use of probiotic Lactic Acid Bacteria (LAB) (e.g. lactobacilli, lactococci, enterococci, bifidobacteria) for human consumption, by proposing criteria, standards, guidelines, and regulations on the one hand, and procedures and standardised methodologies of pre-marketing biosafety testing and post-marketing surveillance on the other hand.

Specific objectives:

Taxonomic description of probiotic and other LAB;

Detection of resistance and horizontal transfer of antibiotic resistance genes among LAB;

Detection of known and new virulence properties of LAB;

Immunological adverse effects of LAB in the EAE model;

Survival, colonisation, and genetic stability of probiotic LAB in the human gut.

(expected) Results and achievements

Culture collection and database of probiotic and other LAB.

Standardised methodologies to detect antibiotic resistance in LAB.

Investigation of (potential) virulence properties in LAB, and their association with clinical disease and results obtained in rat endocarditis model.

Potential immunological adverse effects of LAB.

Genetic stability and colonisation of probiotic LAB in the human gastro-intestinal gut.